This invention relates to a box like an electric junction block such as a relay box, a fuse box or an electric control unit box which is mounted in a vehicle such as a motorcar and incorporates an electric component such as a relay, a fuse or an electric control unit, and more particularly to a box provided with a first cover, a second cover and an interior component housed in an internal space formed when the first cover and second cover are fit to each other and capable of easily detecting the state where one of the first cover and second cover is not correctly assembled with the other thereof (i.e. semi-fitting state).
Traditionally, as the electric junction block mounted in a vehicle, an electric junction block having a waterproof function as described in Patent Reference 1 is known. In the case of this kind of electric junction block, if the cover is not correctly mounted in a complementary member (an electric junction block body or another cover), the waterproof capability will be impaired. So, usually, whether or not the cover is correctly mounted is confirmed by whether or not the cover can be suitably locked.
Patent Reference 1: JP-A-2003-219539
However, even with a structure in which locking cannot usually be done unless the cover is not correctly mounted, as the case may be, if the cover is pushed in with strong force, locking (i.e. engagement) is realized. In this case, even if it is confirmed whether or not the cover is correctly mounted by whether or not the locking can be done, actually, an unsuitable mounting state (i.e. semi-fitting state) may be overlooked.